Industrial Robot

ABSTRACT

An industrial robot has a base for installation, a first arm, a second arm, a third arm, a wire feeder, a welding torch, and a torch cable. The first arm rotates with respect to the base. The second arm pivots with respect to the first arm. The third arm pivots with respect to the second arm. The torch cable is coupled to the wire feeder and feeds a welding wire to a welding torch. The wire feeder is provided to the second arm and is rotatable around a rotation axis.

This application is a U.S. national phase application of PCTInternational Application PCT/JP2006/300989.

TECHNICAL FIELD

The present invention relates to an industrial robot used for welding,for example, and used in floor-mounted or a ceiling-mountedinstallation.

BACKGROUND ART

Conventionally, as an installing and using method of a weldingmulti-joint robot (an industrial robot), floor-mounted use,ceiling-mounted use, or the like, is generally known. FIG. 6 is aperspective view showing such an industrial robot when it is used in astate in which it is mounted on a floor. FIG. 7 is a side view showingsuch an industrial robot when it is used in a state in which it ismounted on a ceiling.

First arm 112 rotates with respect to base 111 for installation. Secondarm 113 pivots with respect to first arm 112, and third arm 114 pivotswith respect to second arm 113. Furthermore, fourth arm 115 pivots withrespect to third arm 114. Welding wire feeder 116 feeds a welding wire.Fixing device 117 fixes welding wire feeder 116 to the industrial robot.Torch cable 118 feeds the welding wire from welding wire feeder 116 towelding torch 119.

In FIG. 6, welding wire feeder 116 is fixed to the upper part of thirdarm 114. Such a configuration is disclosed in, for example, JapanesePatent Unexamined Publication No. 2004-261878. Furthermore, in FIG. 7,welding wire feeder 116 is fixed to the side face of third arm 114. Sucha configuration is disclosed in, for example, Japanese Patent UnexaminedPublication No. H8-57648. Thus, in a conventional welding multi-jointrobot, the position to which welding wire feeder 116 is attached isdifferent between the time of floor-mounted use and the time ofceiling-mounted use. That is to say, the structure (specification) isgenerally different between the floor-mounted use and theceiling-mounted use.

Therefore, when a robot used in a state in which it is mounted on thefloor is used in a state in which it is mounted on the ceiling, or whena robot used in a state in which it is mounted on a ceiling is used in astate in which it is mounted on a floor, the position to which weldingwire feeder 116 is attached has to be changed. In order to correspond tosuch a change, it is necessary to provide fixing positions of wirefeeder 116 for both floor-mounted use and ceiling-mounted use. That isto say, two or more positions to which wire feeder 116 is attached needto be provided. Furthermore, it is necessary to prepare attachingmembers for fixing welding wire feeder 116 corresponding to each useform of floor-mounted use and ceiling-mounted use. Thus, it takes a timeto change the use forms, and the cost therefor rises.

Furthermore, in coupling of a feeder cable for electrically couplingbetween welding wire feeder 116 and the inside the robot, it isnecessary to additionally consider a wiring method corresponding to eachuse form. Thus, it takes a time to change the coupling corresponding tothe use form.

Furthermore, in the structure shown in FIG. 7, welding wire feeder 116is attached to the side face of third arm 114. Therefore, the distancebetween a location of the center of gravity of welding wire feeder 116and the industrial robot (the arm) is increased, and a moment load tofixing device 117 for attaching welding wire feeder 116 is increased.

In order to resist this load, the strength and rigidity of fixing device117 is required to be increased. That is to say, the size and mass of amember constituting fixing device 117 may be increased. Such aconfiguration deteriorates the motion performance of the industrialrobot and adversely affects the approaching performance to a weldingwork and a jig for fixing the welding work.

SUMMARY OF THE INVENTION

An industrial robot of the present invention includes a base forinstallation, a first arm, a second arm, a third arm, a wire feeder, awelding torch, and a torch cable. The first arm rotates with respect tothe base. The second arm pivots with respect to the first arm. The thirdarm pivots with respect to the second arm. The torch cable is coupled tothe wire feeder and feeds a welding wire to the welding torch. The wirefeeder is provided to the second arm and is rotatable around a rotationaxis. In this structure, a position in which the wire feeder is providedis common in a robot used in a state in which it is mounted on a floorand a robot used in a state in which it is mounted on a ceiling. Then,by rotating the wire feeder, floor-mounted use and ceiling-mounted usebecome possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing a state of an industrial robot at the timeof floor-mounted installation in accordance with an exemplary embodimentof the present invention.

FIG. 2 is a side view showing a state of the industrial robot at thetime of ceiling-mounted installation in accordance with the exemplaryembodiment of the present invention.

FIG. 3 is a partial sectional view showing a vicinity of a fixing devicefor a welding wire feeder of the industrial robot in accordance with theexemplary embodiment of the present invention.

FIG. 4 shows a state in which a rotation angle of the welding wirefeeder of the industrial robot is fixed by the fixing device inaccordance with the exemplary embodiment of the present invention.

FIG. 5 is a top view showing the industrial robot in accordance with theexemplary embodiment of the present invention.

FIG. 6 is a perspective view showing a state of a conventionalindustrial robot at the time of floor-mounted installation.

FIG. 7 is a side view showing a state of a conventional industrial robotat the time of ceiling-mounted installation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a side view showing an industrial robot in a state in which itis mounted on a floor in accordance with the present exemplaryembodiment.

FIG. 2 is a side view showing the industrial robot in a state in whichit is mounted on a ceiling. In the following description, the directionof an industrial robot seen from a floor surface or a ceiling surface isdefined as an upper side.

Base 11 is provided to install the industrial robot on a floor surface,a ceiling surface, or the like. First arm 12 rotates with respect tobase 11. Fourth arm 13 pivots with respect to first arm 12, and secondarm 14 pivots with respect to fourth arm 13. That is to say, second arm14 pivots with respect to first arm 12. Third arm 15 pivots with respectto second arm 14. Welding wire feeder (hereinafter, referred to as“feeder”) 16 is provided at the upper side of second arm 14. Torch cable18 feeds a welding wire from feeder 16 to welding torch 19.

Fixing device 17 is provided to attach feeder 16 to second arm 14.Fixing device 17, which has rotation axis 17A for allowing feeder 16 toturn, rotatably fixes feeder 16 and fixes the rotation angle of feeder16. Thus, fixing device 17 fixes feeder 16 at a position in which feeder16 is offset in the horizontal direction to a degree in which torchcable 18 attached to feeder 16 does not interfere with third arm 15.That is to say, feeder 16 is provided to second arm 14 and can rotatearound rotation axis 17A.

Fourth arm 13 is attached like a cantilever to first arm 12 and secondarm 14. That it to say, fourth arm 13 is attached to one side face offirst arm 12 and to one side face of second arm 14. Feeder 16 is locatedon the opposite side to fourth arm 13 relatively to a rotating axis (notshown) of first arm 12. The rotating axis of first arm 12 is an axis forrotatably attaching a first arm 12 to base 11.

If feeder 16 is attached to the same side as fourth arm 13 relatively tothe rotating axis of first arm 12, when second arm 14 pivots, feeder 16interferes with fourth arm 13. Therefore, the operation range of secondarm 14 is restricted. Furthermore, in order to avoid the interference offeeder 16 to fourth arm 13, the position to which feeder 16 is attachedis required to be offset to the outside of fourth arm 13. This structureleads to increase in the size and weight of fixing device 17, resultingin deterioration of the motion performance and approaching performanceto a welding work, etc. in an industrial robot.

When feeder 16 is attached to the opposite side to fourth arm 13relatively to the rotating axis of first arm 12, problems associatedwith interference mentioned above or unnecessary increase in the sizeand weight of fixing device 17 do not arise. Therefore, deterioration ofthe motion performance and approaching performance to a welding work,etc. in an industrial robot can be prevented.

FIG. 3 is a partial sectional view showing a vicinity of fixing device17. Rotating hollow pipe shaft (hereinafter, referred to as “shaft”) 21is provided to fixing device 17 and is located on the rotation center ofthe fixing device 17 to constitute rotation axis 17A. Feeder cable(hereinafter, refereed to as “cable”) 22 electrically couples feeder 16to the inside of the industrial robot. Cable 22 is wired through theinside of shaft 21.

FIG. 4 is a perspective view showing a state in which a rotation angleof feeder 16 is fixed by fixing device 17 at the time of floor-mounteduse shown in FIG. 1. In this case, feeder 16 is fixed facing upward.Note here that rotation fixing portion 31 that is a part of fixingdevice 17 fixes feeder 16 at a predetermined angle.

FIG. 5 partially shows a state in which feeder 16 is fixed on second arm14 at the time of floor-mounted use shown in FIG. 1, which is seen fromthe upper side of the industrial robot to the side of a floor surface.Location of gravity center 41 of schematically represents a location ofthe center of gravity of feeder 16.

Next, in the industrial robot having the above-mentioned configuration,the use form of the industrial robot is described as to the case inwhich floor-mounted use shown in FIG. 1 is changed to theceiling-mounted use shown in FIG. 2 as an example. Firstly, theindustrial robot is fixed to a ceiling surface (not shown) by using base11. Next, feeder 16 is rotated around rotation axis 17A of fixing device17 from the state shown in FIG. 1 to the state shown in FIG. 2 andfixed. That is to say, feeder 16 is fixed facing downward (to the sideof the ceiling). Next, third arm 15 is rotated by 180° into a postureshown in FIG. 2, the industrial robot is made in a state capable ofwelding a work (not shown) located at the side of a floor surface (notshown), for example.

Thus, fixing device 17 for fixing feeder 16 to second arm 14 can becommonly used at the time of floor-mounted use and the time ofceiling-mounted use. That is to say, it is not necessary that fixingdevices are provided independently at the time of the floor-mounted useand the time of ceiling-mounted use. Furthermore, the position to whichthe fixing device is attached is common and the position is not requiredto be changed.

Furthermore, fixing device 17 is provided with rotation axis 17A thatallows feeder 16 to rotate. Then, according to whether floor-mountedinstallation or ceiling-mounted installation, feeder 16 is allowed torotate around rotation axis 17A. Thus, by changing an angle of feeder16, the position of torch cable 18 can be changed into the directionsuitable for the time of the floor-mounted use and ceiling-mounted use.That is to say, an attachment angle of feeder 16 is changed by rotatingfeeder 16 without changing the position to which feeder 16 is attachedbetween the time of floor-mounted use and the time of ceiling-mounteduse. Since only this configuration can correspond to both thefloor-mounted use and ceiling-mounted use of an industrial robot, anindustrial robot with excellent workability can be obtained.

Note here that depending on a method of carrying out welding and a shapeof a welding base material, and the like, torch cable 18 may be requiredto be fixed in order to restrict the interference range of touch cable18. In such a case, by using rotation fixing part 31, a bolt, or thelike, shown in FIG. 4, feeder 16 can be fixed at an angle necessary toavoid interference of torch cable 18.

Furthermore, as shown in FIGS. 3 and 4, cable 22 passes through theinside of shaft 21. With such a structure, even when feeder 16 isrotated, layout of cable 22 inside shaft 21 constituting rotation axis17A is not affected. That is to say, when an industrial robot is changedfrom the floor-mounted use to the ceiling-mounted use, or when anindustrial robot is changed from the ceiling-mounted use to thefloor-mounted use, it is not necessary to change layout or coupling ofcable 22. Therefore, workability associated with the change between thefloor-mounted use and the ceiling-mounted use of the industrial robotcan be improved.

Furthermore, as shown in FIG. 5, in order to allow feeder 16 to rotate,it is preferable that a position to which feeder 16 is attached isoffset to a position apart from third arm 15. At this time, offsettingis carried out at minimum to a degree in which torch cable 18 attachedto feeder 16 does not interfere with second arm 14 and third arm 15.With this attachment position, the distance between location of thegravity center 41 of feeder 16 and a pivot axis of third arm 15 isreduced. Therefore, a moment load applied to fixing device 17 for fixingfeeder 16 to second arm 14 becomes small. Note here that, the shorterthe distance between the location of the gravity center 41 and the pivotaxis of third arm 15 is, the smaller the moment load becomes. Therefore,it is desirable that at least a part of feeder 16 is located on secondarm 14.

As mentioned above, with the configuration in which the distance betweenlocation of the gravity center 41 and the pivot axis of third arm 15 isshort, a strong attachment member for attaching feeder 16 is notrequired to be provided. Thus, the industrial robot can have a compactsize and light weight.

Note here that, in this exemplary embodiment, fourth arm 13 is pivotablyprovided between first arm 12 and second arm 14. However, feeder 16 maybe provided on second arm 14 in an industrial robot that does not havefourth arm 13.

INDUSTRIAL APPLICABILITY

An industrial robot of the present invention can be used both at thetime of floor-mounted use and ceiling-mounted use. Therefore, it isuseful as an industrial robot capable of carrying out welding and thelike, by mounted on a floor, on a ceiling, or the like.

1. An industrial robot capable of being used in a floor-mounted stateand a ceiling-mounted state, comprising: a base for installation; afirst arm rotatably attached to the base; a second arm being pivotablewith respect to the first arm; a third arm pivotably attached to thesecond arm; a wire feeder provided to the second arm and being rotatablearound a rotation axis; a welding torch; and a torch cable for feeding awelding wire to the welding torch, the torch cable coupled to the wirefeeder.
 2. The industrial robot according to claim 1, further comprisinga fixing device including the rotation axis and provided to the secondarm.
 3. The industrial robot according to claim 1, further comprising afeeder cable for electrically coupling between an inside of theindustrial robot and the wire feeder; wherein the rotation axis iscomposed of a rotating hollow pipe shaft, and the feeder cable passesthrough the rotating hollow pipe shaft.
 4. The industrial robotaccording to claim 1, further comprising a rotation fixing part forfixing an rotation angle of the wire feeder.
 5. The industrial robotaccording to claim 1, wherein a position to which the wire feeder isattached is offset to a position apart from the third arm.
 6. Theindustrial robot according to claim 1, wherein at least a part of thewire feeder is located on the second arm.
 7. The industrial robotaccording to claim 1, further comprising a fourth arm pivotably attachedto the first arm and the second arm.
 8. The industrial robot accordingto claim 7, wherein the fourth arm is attached to one side face of thefirst arm and one side face of the second arm, and the wire feeder islocated opposite to the fourth arm relatively to a rotating axis of thefirst arm.